Consumers use a wide range of devices and networks, including cellular phones, paging devices, personal communication services (PCS) systems, and wireless data networks. Wireless service providers create new markets for wireless devices and expand existing markets by making wireless devices and services cheaper and more reliable. Wireless service providers attract new customers by reducing infrastructure costs and operating costs, by increasing handset battery life, and improving quality of service, and new and better features.
Inadequate coverage is a persistent problem in the quality of service of any wireless network. Natural and man-made obstacles frequently create radio frequency (RF) “holes” in the coverage area of a wireless network. Voice and data call connections are frequently dropped when a wireless terminal, such as a cell phone or a similar mobile station, enters an RF hole. Mobile stations that are already in an RF hole may not be able to reliably establish new connections. Typical areas in which RF holes occur include underground tunnels, buildings that have large footprints, tall buildings, and underground shopping malls.
Wireless service providers may attempt to improve coverage by deploying RF repeater transceivers. A variety of repeaters have been developed to improve the coverage of wireless networks. However, in current wireless telecommunications systems, it is well known that the coupling of echo signals between the receive and transmit antennas of a repeater is the primary limiting factor for a good quality wireless repeater.
Various echo-cancellation techniques have been attempted, but often cannot work well in digital repeater applications for a number of reasons. One of the problems that known systems may encounter is the dynamic range difference between the desired signal and the echo signal. Another issue is that in a time-division duplexed (TDD) context, the adaptive filter coefficients cannot be continuously updated in the transition from transmit to receive, or vice versa.
Yet another issue has to do with the computational complexity. The signal input to the signal processing unit is typically ten to sixteen times over-sampled. Working directly with the very high sampling rate data stream as the traditional echo canceller would do should always be avoided.
Therefore, there is a need in the art for an improved system and method for wireless network repeaters.